1. Field of the Invention
This invention pertains in general to a telephone distribution network and, more particularly, to a telephone network interface device for connection with a telephone distribution cable and a drop wire service.
2. Description of the Related Art
Utilization of the high frequency spectrum in telephone cables has become practical with high speed modems that combat distortions attributed to the physical construction of the cables and cable topologies. While much of the telephone distribution cable in use today is physically constructed such that radiation of Radio Frequencies (RF) from the cable can be controlled through installation and maintenance practice, drop wires, or the connection from the telephone distribution cable to customer premises, and customer premise wiring does not provide the same controlled environment and thus expose the telephone network to noise ingress from multiple sources. The drop and in-house wiring may also radiate high frequency signals that would otherwise be contained within the telephone network distribution cables. The egress and previously mentioned ingress are undesirable.
Therefore, while providing for normal operations of a telephone network for voice-band frequencies and below, there is a need to prevent a drop wire or in-home wiring from radiating high frequency signals. There is also a need to prevent high frequency noise energy present on such wiring from entering the controlled environment of the distribution cable.
Accordingly, the present invention is directed to a network interface device that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
To achieve these and other advantages, and in accordance with the purpose of the invention as embodied and broadly described, there is provided a telephone frequency network interface that includes a first network device having high input impedance receiving broadband signals including voice band signals from a telephone network and a second set of signals having frequencies higher than the voice band signals from a first drop wire terminating at a first customer premise, the first network device transmitting only the voice band signals to a first interface port, the first interface port coupled the first network device and a second drop wire terminating at a second customer premise for providing the voice band signals to the drop wire, a second network device having high input impedance coupled to the first network device and the first interface port, the second drop wire providing a third set of signals having frequencies higher than the voice band signals, the second network device attenuating the third set of signals.
In one aspect of the invention, the first network device and the second network device are selectable to transmit the broadband signals.
Also in accordance with the present invention, there is provided a telephone frequency network interface that includes a first interface port receiving a first set of signals from a telephone network, a second interface port, a third interface port, a first network device having high input impedance including a first device port coupled to the first interface port, and a second device port coupled to the second interface port, where the first network device attenuates signals having frequencies high than that of the first set of signals, and a second network device having high input impedance including a first device port coupled to the second interface port and the second device port of the first network device, and a second device port coupled to the third interface port.
In one aspect of the invention, the second network device is configured as an open circuit.
In another aspect of the invention, the first interface port is coupled to a first drop wire to receive a second set of signals having frequencies higher than the first set of signals, the first network device attenuating the second set of signals and preventing the second set of signals from being transmitted to the second interface port or the third interface port.
In yet another aspect of the invention, the second interface port is coupled to a second drop wire and receives a third set of signals having frequencies higher than the first set of signals, and the second network device attenuates the third set of signals and prevents the third set of signals from being transmitted to the third interface port.
Additionally in accordance with the present invention, there is provided a telephone frequency network interface that includes a first network device configured as a filter receiving a first set of signals from a telephone network and a second set of signals having frequencies higher than the first set of signals from a digital subscriber line service, the first network device having high input impedance and attenuating the second set of signals, the first network device providing an output including only the first set of signals, a second network device configured as a filter coupled to the first network device for receiving the output of the first network device, and a first drop wire coupled between the first network device and the second network device receiving only the first set of signals.
In one aspect of the invention, the first network device and the second network device are selectable such that the second network device providing an output including the first set of signals and the second set of signals.
Also in accordance with the present invention, there is provided a telephone frequency network interface method that includes providing a first network device configured as a filter, receiving a first set of signals from a telephone network, receiving a second set of signals having frequencies higher than the first set of signals, and providing a second network device configured as a filter coupled to the first network device, the second network device receiving from the first network device either a first output including only the first set of signals, or a second output including both the first set of signals and the second set of signals.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structures and methods particularly pointed out in the written description and claims thereof, as well as the appended drawings.